So, hire bots. Use C-bills and MC to fill out the slots. Quality goes by price. The player will not be able to complain, if they did not hire the best.
Naturally, the player will not earn the XP that the bots might receive. The bots would have to be hired every match. The mechs should come from the player's own stable.
The bots should be commanded from the battlegrid. The player's mech will need a command console.
This eliminates the animosity among players on a team, and allows a single player the chance to make 12 kills... that's what your other teammates are for, right? Take all the damage, and let you have the glory and money, with no backtalk?

Of course, this might need to be a separate queue/mode in it's own right. MWO: Company Commander. That would quash "pay to win" complaints.